Control method and system for assembling tapered bore bearings using a hydraulic system

Abstract

This application discloses a control method and system for assembling tapered bore bearings using a hydraulic system, relating to the field of intelligent manufacturing technology for high-end equipment. Addressing three core technical challenges—distortion in displacement measurement due to hydraulic nut deformation, blind spots in process status monitoring, and lack of active safety protection under severe faults—this invention employs a deformation-isolated, bridge-type rigid reference to obtain the bearing's true axial displacement. Based on pressure and displacement data, it calculates the instantaneous equivalent press-fit stiffness and identifies the idle stroke, contact and interference establishment, and critical assembly completion stages according to the evolution trajectory, implementing phased adaptive closed-loop control. It executes fault diagnosis and endpoint judgment for mechanical jamming and hydraulic leakage in parallel with the highest hardware interrupt priority, achieving millisecond-level active protection and precise capture of the optimal endpoint. This significantly improves the assembly accuracy and safety of heavy-duty bearings and is applicable to the assembly of key components in engineering machinery such as tunnel boring machines and large cranes.

Description

Technical Field

[0001] This application relates to the field of intelligent manufacturing technology for high-end equipment, and in particular to a control method and system for assembling tapered bore bearings using a hydraulic system in the field of engineering machinery. Background Technology

[0002] Tapered bore bearings (such as spherical roller bearings and tapered roller bearings) are key components in engineering machinery such as the main drive of tunnel boring machines, the slewing bearing of large crawler cranes, and the power head of rotary drilling rigs. The quality of their interference fit with the shaft directly determines the operating accuracy, load-bearing capacity, and service life of the entire machine under harsh conditions such as heavy loads and impacts. Currently, the hydraulic nut method is the industry-recognized standard process for interference fitting of such large, heavy-duty tapered bore bearings (see the paper published by Wang Yanpeng et al.: Application of Hydraulic Nuts in Tapered Bore Rolling Bearing Assembly Technology, which records relevant information). This method involves injecting high-pressure oil into the annular oil chamber of the hydraulic nut, driving the piston to generate a huge axial thrust, forcing the inner ring of the bearing to slide along the tapered surface to obtain a preset radial interference.

[0003] However, existing technological solutions reveal the following systemic defects stemming from physical mechanisms when dealing with the increasingly demanding heavy-load, ultra-high-pressure, and highly nonlinear assembly scenarios of modern engineering machinery:

[0004] 1. Difficulty in ensuring accuracy and consistency: Single-parameter automatic control (such as monitoring only pressure or only displacement) is prone to "pressure meets the standard but displacement is insufficient" or vice versa, and cannot accurately capture the "optimal assembly endpoint". Uncontrolled interference directly leads to early equipment failure.

[0005] 2. Lack of proactive safety protection for severe working conditions: When jamming occurs during assembly, the pressure rises sharply while the displacement stops. When leakage occurs, the pressure cannot be established and the displacement is minimal. Existing systems may not be able to detect this abnormal correlation between the two parameters simultaneously, or even if they are detected, they may have to rely on operator reaction. The system itself does not have the ability to perform real-time intelligent diagnosis based on multi-dimensional dynamic relationships and immediately shut down the machine. This can easily lead to permanent damage to expensive core components such as bearings and journals.

[0006] 3. The black box nature of process data leads to a lack of data foundation for quality traceability and process optimization: Due to the lack of synchronous recording and storage of the pressure-displacement (PS) curve throughout the entire process, the assembly process becomes a "black box," making it impossible to trace the root cause of quality problems, and the optimization of process parameters also lacks objective and quantitative data support.

[0007] 4. Low level of system integration, making it difficult to integrate into the digital manufacturing system: Existing solutions are mostly isolated single-machine devices that do not generate structured quality data packages containing process characteristic curves, making it difficult to integrate with manufacturing execution systems (MES) or product lifecycle management (PLM) systems, thus forming "information silos".

[0008] In summary, existing technologies have failed to address the core challenges of accurately sensing, intelligently making decisions, providing real-time safety protection, and achieving data traceability for complex nonlinear processes in the hydraulic assembly of heavy-duty tapered bore bearings in engineering machinery. Therefore, a control method and system for tapered bore bearing assembly is urgently needed to solve these technical problems. Summary of the Invention

[0009] This application provides a control method and system for assembling tapered bore bearings using a hydraulic system, for the efficient assembly of tapered bore bearings.

[0010] In a first aspect, this application provides a control method for assembling tapered bore bearings using a hydraulic system, comprising:

[0011] Step S100: Begin;

[0012] Step S200: Collect pressure data of the hydraulic system and displacement data of the bearing, and preprocess the data;

[0013] Step S300: Based on pressure data and displacement data, obtain the equivalent press-fit stiffness;

[0014] Step S400: Based on the equivalent press-fit stiffness, determine the current assembly stage according to the predetermined rules, and execute the endpoint judgment strategy and the abnormal judgment strategy. If either the endpoint judgment strategy or the abnormal judgment strategy is met, execute the shutdown process; otherwise, proceed to the next step.

[0015] Step S500: Apply different control strategies to the hydraulic system according to the different assembly stages in step S400, and then return to step S200.

[0016] Preferably, step S100 includes steps S110 and S120;

[0017] Step S110: Load preset process parameters;

[0018] Step S120: Calculate the dynamic benchmark interval based on historical qualified data. ,include:

[0019] Step S121: Historical Data Filtering

[0020] Retrieve from the database based on the specifications of the workpiece to be assembled;

[0021] Select the most recent Historical records of substandard assembly;

[0022] Step S122: Data Extraction and Processing

[0023] From each selected historical record, extract the original data sequence of its contact and interference establishment phases to obtain... Set of data pairs: , and Representing the first The displacement sequence and stiffness sequence in the record, ;

[0024] The original displacement data and equivalent press-fit stiffness data of each sequence are filtered;

[0025] Instantaneous equivalent press-fit stiffness in each sequence First satisfaction The data points are used as the contact start point. This represents the contact initiation stiffness threshold. Using this contact initiation point as the displacement reference, the displacement coordinates of each sequence are zeroed out, and the data from the empty travel stage before the contact initiation point are discarded. The sequences are aligned along the displacement axis using the same physical starting point. Let the common displacement analysis interval used to construct the dynamic reference interval after alignment be denoted as . ;

[0026] Common displacement interval Evenly divided into Discrete displacement points: ;

[0027] Step S123: Calculation of statistics

[0028] For each discrete displacement point By using linear interpolation, the discrete displacement points of each sequence are obtained. The corresponding stiffness value This forms a set of stiffness samples for that displacement point: ;

[0029] Through formula Calculate the mean of the baseline interval, where This represents the mean of the baseline interval. Indicates the first The sequence in The stiffness value; Indicates the smoothing factor; Indicates based on the previous The previous round calculated from the sequence Mean;

[0030] Based on stiffness sample set Calculate the standard deviation of this set. Used to quantize at the displacement point Within the normal fluctuation range of stiffness;

[0031] Step S124: Generate the dynamic reference interval for this assembly.

[0032] Through formula Calculate the lower boundary function of the dynamic reference interval. , Indicates the coverage factor;

[0033] Through formula Calculate the upper boundary function of the dynamic reference interval .

[0034] Preferably, in step S300, after real-time filtering of the collected pressure and displacement data, a pressure-displacement curve is dynamically constructed, and the instantaneous equivalent press-fit stiffness is calculated in real time using the finite difference method. , , Indicates the hydraulic system at the previous moment Up to the current moment The pressure increase, Indicates the moment before the bearing Up to the current moment The displacement increment.

[0035] Preferably, when Below the preset minimum threshold At that time, pause updates used for decision-making. The value is determined and the valid value from the previous moment is retained. The valid value from the previous moment is then used for judgment in step S400.

[0036] Preferably, the predetermined rules for determining the assembly stage in step S400 include:

[0037] If in the first consecutive time window If all three conditions are met simultaneously, it is determined to be an empty travel phase;

[0038] Condition 1, Core Stiffness Criterion 1: , Indicates instantaneous equivalent press-fit stiffness; Indicates the contact initial stiffness threshold;

[0039] Condition 2, Effective Displacement Criterion: Rate of Change of Displacement ; Indicates the minimum effective speed threshold;

[0040] Condition 3, Low-pressure state criterion: Current moment pressure and , Indicates the initial contact pressure threshold. Indicates the upper limit of safety pressure during no-load travel;

[0041] If it continues If conditions four and five are met simultaneously within a certain time period, it is determined to be the contact and interference establishment stage;

[0042] Condition 4, Core Stiffness Criterion 2: lie in Within the interval, This represents the lower boundary value of the dynamic reference interval corresponding to the current displacement point. This represents the upper boundary value of the dynamic reference interval corresponding to the current displacement point;

[0043] Condition 5, Criterion 1 for rate of change: In the above Within a given time period, the equivalent press-fit stiffness satisfies the non-decreasing condition at the window endpoints:

[0044]

[0045] in, Indicates instantaneous equivalent press stiffness. Indicates the time Instantaneous equivalent compression stiffness at the initial moment, This indicates the preset noise tolerance threshold.

[0046] If conditions six, seven, and eight are met simultaneously, the assembly is considered to be in the critical stage of completion.

[0047] Condition 6, Stiffness Detachment Criterion: continued Time greater than and , Indicates the relative out-of-tolerance threshold;

[0048] Condition 7, Criterion 2 for rate of change: Rate of change of equivalent press-fit stiffness , This represents the critical rate of change threshold;

[0049] Condition 8, Displacement Safety Criterion: , Indicates the current time The displacement, This indicates the minimum displacement threshold determined according to the design drawings.

[0050] Preferably, the endpoint determination strategy includes satisfying the following two conditions in addition to meeting the critical stage conditions for assembly completion:

[0051] Condition 9, Physical State Channel Criterion: and ,in, Indicates the material's saturation stiffness threshold;

[0052] Condition 10, Criteria for Process Parameter Channels: and , This represents the minimum displacement threshold determined according to the design drawings. This indicates the maximum displacement threshold determined according to the design drawings; This represents the expected lower limit of pressure, determined based on the minimum allowable interference in the design. This indicates the upper limit of the expected pressure, determined based on the maximum allowable interference in the design.

[0053] Preferably, the anomaly detection strategy includes diagnoses that satisfy any one of the following:

[0054] The first item, diagnosis of jamming and cold welding faults, includes the judgment criteria in the second continuous time window. Both conditions eleven and twelve are satisfied simultaneously.

[0055] Condition 11, Criterion for Abnormal Pressure-Displacement Relationship: , Indicates instantaneous equivalent press stiffness. Indicates the safety factor for jamming; This represents the upper boundary value of the dynamic reference interval corresponding to the current displacement point;

[0056] Condition 12, Criterion for Displacement Stagnation: Rate of Change of Displacement absolute value , Indicates the displacement stagnation threshold;

[0057] The second item is the diagnosis of hydraulic system leaks and failures. The judgment criteria include timing from the issuance of the start press-fit command within a preset leak diagnosis time window. The condition simultaneously satisfies conditions thirteen, fourteen, and fifteen.

[0058] Condition 13, Failure Criterion for Pressure Establishment: consistently less than , This indicates the pressure build-up threshold of the hydraulic system;

[0059] Condition 14, Criterion for Invalid Displacement Growth: Less than , Indicates time window The actual cumulative displacement increment within, Indicates the invalid displacement threshold;

[0060] Condition 15, Criterion for System Stiffness Anomaly: Time Window Average equivalent press-fit stiffness obtained from internal calculation , This represents a stiffness anomaly setting factor less than 1. Indicated based on lower boundary function Time window Displacement point at the start time The corresponding lower limit of stiffness;

[0061] The third item is the absolute safety boundary diagnosis, and the judgment condition includes meeting one of condition sixteen or condition seventeen.

[0062] Condition 16, Pressure Boundary: , This represents the absolute maximum pressure determined by the component material strength and safety factor.

[0063] Condition 17, Displacement Boundary: , It represents the absolute maximum displacement determined by the design drawings and fit tolerances.

[0064] Preferably, in step S400, the shutdown process includes performing different shutdown operations based on the shutdown reason;

[0065] If the endpoint judgment strategy is met, the hydraulic system is controlled to stop pressurizing and maintain pressure for a period of time before stopping and depressurizing.

[0066] If the jamming and cold welding faults in the abnormal judgment strategy are met or the safety boundary is exceeded, the hydraulic system is controlled to shut down and depressurize in an emergency.

[0067] If the leakage and failure faults in the anomaly judgment strategy are met, the hydraulic system is controlled to shut down urgently and the alarm procedure is initiated.

[0068] Preferably, the shutdown process also includes generating an electronic record after the shutdown operation is performed;

[0069] Electronic archives include task identifiers, time-series data, event logs, and parameters and results;

[0070] The task identifier includes a unique task ID, bearing model, operator, equipment number, and timestamp;

[0071] Time-series data includes time, pressure, displacement, and equivalent press-fit stiffness;

[0072] The event log includes the start and end points of the assembly stages and abnormal event points recorded in chronological order;

[0073] The parameters and results include the preset process parameters, the actual control parameters, the final assembly results, and key result data including the final displacement.

[0074] Preferably, in step S500, different control strategies are adopted for the hydraulic system according to different assembly stages, including:

[0075] If it is in the no-stroke stage, a fixed opening command is output to the hydraulic system to drive the hydraulic system at a constant flow rate. This operation allows the drive end of the hydraulic system to achieve a constant propulsion speed. ;

[0076] If the system is in the contact and interference setup phase, then the closed-loop control steps are initiated, including first calculating... and deviation , Indicate the midline of the dynamic reference interval, then The input is sent to the proportional-integral (PI) controller, which then outputs the pressure regulation amount. Finally, a new pressure setpoint is generated. And Send to the hydraulic system for execution, to achieve instantaneous equivalent press-fit stiffness Stable within the dynamic reference range Inside;

[0077] If the assembly is at a critical stage, reduce the flow rate of the hydraulic system to the preset endpoint detection flow rate. , .

[0078] Preferably, during the contact and interference fit establishment phase, if the instantaneous equivalent press-fit stiffness... Exceeding the dynamic reference range Then, the regression control steps are executed, including:

[0079] Step 1: Let ;

[0080] Step 2: Start a time period of Observation timer;

[0081] Step 3: If in Inside, If the system returns to the dynamic reference range, the closed-loop control steps continue; otherwise, the hydraulic system is shut down and an alarm procedure is initiated.

[0082] Secondly, this application provides a control system for assembling tapered bore bearings using a hydraulic system, comprising:

[0083] The sensing unit includes a pressure sensor and a displacement sensor, both connected to the control unit. The pressure sensor is connected to the hydraulic system to acquire pressure data, and the displacement sensor is set to correspond to the bearing to be installed to acquire the bearing displacement data.

[0084] The control unit has a built-in control method for assembling tapered bore bearings using a hydraulic system. This method controls the hydraulic system, which drives the bearing to be installed to move axially.

[0085] The data storage and interaction unit is bidirectionally connected to the control unit.

[0086] The control method and system of this application have at least the following beneficial effects:

[0087] The control method of this application simultaneously collects pressure and displacement parameters, obtains the equivalent press-fit stiffness based on the dual parameter data, and determines the current assembly progress, i.e., the current assembly stage, based on the equivalent press-fit stiffness. Then, different control strategies are adopted for the hydraulic system according to different assembly stages, so that the hydraulic system matches different working parameters at different assembly stages, achieving high-precision and high-reliability assembly. After the control work at the current moment is completed, the system returns to continue collecting data to achieve closed-loop control. While determining the assembly stage, the system also determines in parallel whether the bearing has reached the end position of the assembly or whether the assembly work has encountered an abnormality based on the equivalent press-fit stiffness, and executes the shutdown procedure in a timely manner. This method can accurately and effectively capture the optimal assembly end point and provide active safety protection in case of abnormalities. Attached Figure Description

[0088] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0089] Figure 1 This is a schematic diagram of the hydraulic system in Embodiment 1 of this application;

[0090] Figure 2 This is a flowchart of the control method in Embodiment 2 of this application;

[0091] Figure 3 This is a flowchart of step S100 in Embodiment 2;

[0092] Figure 4 This is a schematic diagram of determining the conditions required for the assembly stage in step S400;

[0093] Figure 5 This is a schematic diagram of the conditions required to determine the endpoint in step S400;

[0094] Figure 6 This is a comparison chart of the theoretical pressure-displacement curve and the abnormal curve in Example 2;

[0095] Figure 7This is a schematic diagram of the conditions required to determine the anomaly in step S400;

[0096] Figure 8 This is a schematic diagram of the shutdown process in Example 2;

[0097] Figure 9 This is a flowchart of step S500;

[0098] Figure 10 This is a schematic diagram of the control system in Embodiment 3 of this application;

[0099] The annotations in the attached figures are explained as follows:

[0100] 100. Bearings;

[0101] 200. Support base;

[0102] 300. Rigid support;

[0103] 400. Hydraulic nut; 410. Hydraulic nut body; 420. Hydraulic nut piston; 400a. Pressure oil;

[0104] 500, journal;

[0105] 600. Pressure sensor;

[0106] 700. Displacement sensor; Detailed Implementation

[0107] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0108] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0109] Example 1:

[0110] This embodiment discloses a hydraulic system for assembling tapered bore bearings. First, the bearing in this embodiment needs to be installed on a journal with a tapered surface. The bearing is clamped and assembled by sliding axially relative to the tapered surface. Of course, in addition to the journal, the bearing can also be installed on any other component with a tapered surface. This embodiment takes the journal as an example.

[0111] like Figure 1 As shown, the hydraulic system of this embodiment includes a support base, a rigid support, a hydraulic nut, and a pressure supply unit, as described below:

[0112] The bracket base is detachably mounted on the journal. Detachable installation methods include thread engagement, shaft end bolts, precision clamps, etc. (Magnetic attraction is unreliable under heavy load conditions, so it is not recommended). The bracket base is mounted on a stationary journal, forming a high-rigidity independent base.

[0113] The rigid bracket has a C-shaped cross-section. One end of the rigid bracket is fixedly connected to the bracket base, and the other end is used to install a displacement sensor (the displacement sensor is used to measure the axial displacement data of the bearing). Specifically, the rigid bracket extends from the bracket base and horizontally spans the hydraulic nut. There is a visible physical isolation gap between the inner surface of the rigid bracket and the outer surface of the hydraulic nut, as well as between the rigid bracket and the bearing to be installed. The width of this gap is greater than the sum of the elastic deformation and thread runout of the hydraulic nut under the maximum working pressure (usually more than 0.5 mm is reserved). The physical isolation gap ensures that the deformation of the hydraulic nut cannot be transmitted to the rigid bracket.

[0114] The hydraulic nut is coaxially sleeved on the journal and is used to drive the bearing to be installed to move axially relative to the journal. The hydraulic nut is a conventional component in this field and will only be briefly introduced here. The hydraulic nut includes a hydraulic nut body and a hydraulic nut piston. The hydraulic nut body is coaxially sleeved on the journal, and the hydraulic nut piston is slidably disposed on the hydraulic nut body. The hydraulic nut piston is used to directly contact the end face of the bearing to be installed and drive the bearing to move axially relative to the journal to obtain a preset interference fit.

[0115] The pressure supply unit serves as the power output end, comprising an ultra-high pressure hydraulic pump station and a high-response electro-hydraulic proportional valve. The pressure supply unit receives and executes commands from the control unit to achieve precise and stepless regulation of the output pressure and flow. The high-pressure hydraulic pump station, the high-response electro-hydraulic proportional valve, and the hydraulic nut are connected in sequence.

[0116] Furthermore, the external sensing unit includes a pressure sensor and a displacement sensor. The displacement sensor is mounted on a rigid bracket and is used to measure the axial displacement data of the bearing to be installed. The pressure sensor is connected to the pressure supply unit, specifically between the high-response electro-hydraulic proportional valve and the hydraulic nut, and is used to acquire the pressure data of the hydraulic system.

[0117] In this embodiment, the isolated rigid support structure can completely eliminate the interference of axial elastic deformation (usually 0.1-0.3mm) and thread clearance movement of the hydraulic nut under high pressure on displacement measurement, thus resolving the contradiction of measurement distortion.

[0118] Example 2:

[0119] like Figure 2 As shown, this embodiment two discloses a control method for assembling tapered bore bearings using a hydraulic system. The hydraulic system in this embodiment is configured as the hydraulic system in embodiment one. The control method of this embodiment two includes the following steps S100, S200, S300, S400, and S500.

[0120] Step S100 includes steps S110 and S120;

[0121] Step S110: After pressing the start assembly button, the parameters related to the workpiece (bearing and journal) model and material, as well as preset parameters, are automatically loaded, including at least the following parameters:

[0122] Parameter 1: Contact initial stiffness threshold , based on The calculation method was determined through an unloaded calibration experiment: a background stiffness sequence was collected under unloaded conditions, and its mean was calculated based on the statistical 3σ principle. with standard deviation Set the value to , where the coefficient The value range is 3~5 (corresponding to a confidence level of 99.7%~99.9%). At the same time, considering the influence of temperature changes on hydraulic oil viscosity, periodic dynamic calibration can be performed to compensate for flow resistance fluctuations.

[0123] Parameter 2: Upper boundary of the common displacement analysis interval , The value is determined based on the statistical upper limit of the maximum effective displacement of the selected historical qualified dataset during the contact and interference establishment phase;

[0124] Parameter 3: Coverage Factor The value ranges from 2.0 to 3.0, for example, 2.5;

[0125] Parameter 4: Minimum Threshold This is used to determine whether the displacement change is effective, in order to avoid instability in differential calculations when the displacement increment is too small. , The value of the displacement sensor resolution is determined by the sensor selection. This is a multiple of the safety factor, ranging from 3 to 5, and is determined based on sensor application engineering practices. The peak value of the equivalent displacement noise caused by the inherent pulsation of the hydraulic system is obtained through pressure pulsation analysis under no-load conditions. In addition, the minimum threshold value is... It can also be set according to actual needs;

[0126] Parameter 5: First continuous time window The preferred value is within 3 to 5 control cycles (approximately 30 to 500 cycles). );

[0127] Parameter 6: Minimum effective speed threshold The preferred value is 0.01 mm / s. This threshold is determined by collecting displacement data under no-load and static conditions, calculating the standard deviation of its velocity fluctuation, and then... The principles have been established.

[0128] Parameter 7: Initial contact pressure threshold , =5MPa, preferred The bearing is calibrated according to its specifications and journal dimensions, and is used to physically distinguish the non-contact state.

[0129] Parameter 8: Upper limit of safe pressure during no-load stroke The absolute safety boundary is set according to the hydraulic system and the yield strength of the workpiece material. For example, 30% to 50% of the pressure corresponding to the material's yield limit is used as the absolute safety boundary.

[0130] Parameter 9: Set stability duration threshold Preferred ;

[0131] Parameter 10: Noise Tolerance Threshold , ,in, Defined as the coefficient described in parameter one (Value range 3~5) and standard deviation of the unloaded background stiffness sequence The product of, i.e. This threshold is used as a noise fluctuation tolerance when judging the stiffness evolution trend.

[0132] Parameter 11: Set duration Preferred ;

[0133] Parameter 12: Relative Exceedance Threshold , =0.15~0.25, preferred The value of is determined statistically based on the inflection point of the strain hardening curve of bearing steel, marking the beginning of the material entering the nonlinear strengthening region;

[0134] Parameter 13: Critical Rate of Change Threshold Preferred It is a calibration value greater than zero, which is further optimized. The value should be more than twice the maximum stiffness growth rate during the normal interference build-up phase. Based on the nonlinear evolution law of the contact stiffness of the target bearing ring material during the interference fit process, combined with the mechanical response under dynamic load, and empirical values ​​calibrated through process tests, it is used to identify the critical node where the contact state changes from the elastic stage to local plastic crushing during the assembly process.

[0135] Parameter 14: Minimum displacement threshold determined according to the design drawings ;

[0136] Parameter 15: Maximum displacement threshold determined according to the design drawings ;

[0137] Parameter 16: The expected lower limit of pressure determined based on the minimum allowable interference in the design. :

[0138] Parameter 17: The upper limit of the expected pressure, determined based on the maximum allowable interference fit in the design. ;

[0139] Parameter 18: Material Saturation Stiffness Threshold This threshold is used to indicate whether the bearing mating surfaces have entered a state of full plastic contact or interference saturation. Based on The calculation method involves collecting no fewer than 30 sets of assembly press-fit data. For each set, the equivalent press-fit stiffness characteristic value (e.g., the mean value) is extracted from the interval after the critical stage judgment conditions for assembly completion (i.e., conditions six, seven, and eight are simultaneously met) are met until the stop command is issued. This forms a sample set, and the mean value is calculated. with standard deviation ,set up ,in =1.5~2.0, which corresponds to a 93%~97% confidence level and is consistent with the ratio of the ultimate tensile strength to the yield strength of typical steel.

[0140] Parameter 19: Second Continuous Time Window Preferred It takes 50ms;

[0141] Parameter 20: Stall Safety Factor , It is a constant greater than 1, preferably =3.0, this coefficient is determined based on the statistical analysis of the stiffness surge multiple when jamming occurs in the fault simulation experiment;

[0142] Parameter 21: Displacement Stagnation Threshold This is used to determine whether the axial displacement has stopped. In this embodiment, it is preferred. =0.05-0.1mm / s.

[0143] Parameter 22: Leakage Diagnosis Time Window Preferred =2.0s;

[0144] Parameter 23: Pressure build-up threshold of the hydraulic system , According to the minimum pressure calibration of the hydraulic system from no-load to start-up, for example This is equal to 0.2 to 0.4 times the maximum assembly pressure allowed by the process for this bearing model;

[0145] Parameter 24: Invalid Displacement Threshold , The preferred value is 10 times the resolution of the displacement sensor, for example... =0.01mm;

[0146] Parameter 25: Abnormal Setting Coefficient Preferred Less than 1, further optimization =0.5;

[0147] Parameter 26: The absolute maximum pressure determined by the component material strength and safety factor. , Specifically, the absolute maximum pressure is determined by the material strength and safety factor of the bearings, journals, and pressure-bearing components of the hydraulic system. The absolute maximum pressure... The calculation is as follows:

[0148]

[0149] , , These are the minimum yield pressures for bearings, journals, and pressure-bearing components of hydraulic systems, respectively. Indicates the safety factor, generally Greater than 1, The specific values ​​are determined according to the general safety standards for mechanical design;

[0150] Parameter 27: The absolute maximum displacement determined by the design drawings and fit tolerances. ;

[0151] Parameter 28: Observation timing duration Preferred =150ms.

[0152] Step S120:

[0153] This step aims to dynamically generate a core benchmark for process monitoring for each new assembly task, namely the equivalent press-fit stiffness. dynamic reference range .

[0154] This embodiment calculates the instantaneous equivalent press-fit stiffness in real time based on synchronously and in real-time collected pressure and displacement data. And continuously track its evolution trajectory. The instantaneous equivalent press-fit stiffness of this embodiment As a system-level state variable, its numerical change dynamically reflects the coupling effect of multiple factors such as hydraulic system flow resistance, conical surface friction and material contact stiffness. In the idle stroke stage, it mainly reflects the hydraulic system flow resistance. In the contact and interference establishment stage, it mainly reflects the coupling effect of conical surface dynamic friction and material contact stiffness. In the critical stage of assembly completion, the influence of material elastic-plastic deformation is superimposed. Indicates the hydraulic system at the previous moment Up to the current moment The pressure increase, Indicates the moment before the bearing Up to the current moment The displacement increment. The preferred equivalent press-fit stiffness is normalized by the piston area of ​​the hydraulic nut.

[0155] Dynamic reference range It is a reasonable range that is derived from historical qualified data statistics and varies with the assembly process (with the actual displacement as the independent variable). It serves as the objective basis for the system to determine the state of the contact and interference establishment stage, perform closed-loop control, and determine the subsequent endpoint and anomaly.

[0156] Specifically, this involves designing a qualified assembly process database, where each record corresponds to a single successful assembly in history, and must include information from the contact and interference setup phases (since...). From, to (Before leaving the stable rising range, the complete and synchronous real axial displacement and the calculated equivalent press-fit stiffness data sequence are obtained.)

[0157] After the staff selects the bearing model and starts a new task, they should follow these steps to generate the dynamic reference range for this task, such as... Figure 3 As shown.

[0158] Step S121: Historical Data Filtering

[0159] Selection criteria: Based on the bearing model, material, journal specifications, and material to be assembled, the data is retrieved from the database;

[0160] Sample size and quality: Select the most recent Historical records of substandard assemblies, preferred ≥30, to ensure statistical significance, and to remove records with incomplete process data. If the number of qualified historical records in the database is insufficient, a minimum sample size is preset. When the assembly is successful, the corresponding number of theoretically qualified data can be added to the database, or manually recorded and tested qualified data can be filled in. Alternatively, the generation step of the dynamic reference interval can be skipped for this assembly, and the fixed empirical stiffness interval built into the control unit can be used as the initial control reference. After the assembly is successful, the collected displacement-stiffness data sequence is stored in the database. When the cumulative number of qualified records reaches a certain threshold, the database will be updated accordingly. Subsequently, the assembly process automatically switches to a control mode based on a dynamic reference range.

[0161] Step S122: Data Extraction and Preprocessing

[0162] Feature data extraction: From each selected historical record, extract the original data sequence of its contact and interference establishment phases to obtain a set of N data pairs: ,in and Representing the first The displacement sequence and stiffness sequence in the record. Indicates from the first The axial displacement sequence data extracted from the historical qualified assembly records. The subscripts are... It is a record number. , Indicates from the same article (the first one) Extracting relevant entries from historical records. The instantaneous equivalent press-fit stiffness sequence data calculated synchronously.

[0163] Preprocessing:

[0164] Signal filtering: For each set of sequences, the original displacement data and equivalent press-fit stiffness data are filtered by a digital low-pass filter with a cutoff frequency of 10Hz. This cutoff frequency is set to be less than 1 / 5 of the natural frequency of the hydraulic system in order to suppress high-frequency pulsation of the hydraulic system and environmental mechanical vibration noise.

[0165] Displacement axis alignment: based on their respective "contact start points" (i.e. First satisfaction Using the data points as a benchmark, all The displacement coordinates of each sequence are reset to zero to eliminate installation position errors between batches. Let the common displacement interval after alignment be... .

[0166] Displacement domain discretization: dividing the common displacement interval Evenly divided into Discrete displacement points: . The value of should ensure that the distance between adjacent points can fully reflect the details of stiffness changes. For example, the corresponding displacement step size should not be greater than 0.01 mm. This step size is less than twice the resolution of the displacement sensor to ensure interpolation accuracy.

[0167] Step S123: Statistical calculation (at each discrete displacement point) (Perform), for each displacement point :

[0168] Sample value collection: Through linear interpolation, the value at each displacement point is obtained from each aligned and filtered historical sequence. The corresponding stiffness value This forms a set of stiffness samples for that displacement point: .

[0169] Calculate the Exponentially Weighted Moving Average (EWMA) statistic:

[0170] mean According to the formula calculate, This represents the latest sequence (i.e., the Nth historical data item) within the current calculation period. Stiffness value of a point Represents the smoothing factor, 0 < <1, preferred =0.2, this factor gives higher weight to recent qualified data, so that the baseline interval can adapt to the slow drift of the process.

[0171] Based on the first N-1 sequences (i.e., the first N-1 sequences) The average value of the previous round was calculated from historical data.

[0172] Standard deviation Based on displacement points Stiffness sample set at the location Calculate the sample standard deviation of this set. Used to quantify at the displacement point The normal fluctuation range of stiffness.

[0173] Step S124: Generation of dynamic benchmark interval function

[0174] Based on each displacement point The statistics are used to generate the upper and lower boundary functions of the dynamic benchmark interval:

[0175] ;

[0176] ;

[0177] in, The function representing the lower boundary of the dynamic reference interval. The function representing the upper boundary of the dynamic reference interval; The coverage factor is a configurable parameter used to define the interval width. Based on statistical principles, the optimal value range is 2.0 to 3.0, which corresponds to a confidence level of 95% to 99.7%, effectively identifying anomalies while accommodating normal process fluctuations.

[0178] In this embodiment, the dynamic baseline interval for this task is calculated through the above steps. The dynamic baseline interval is used for subsequent operations.

[0179] Status determination: Determine the real-time calculation Is it located in Within the range, this confirms whether the process is in a stable elastic overshoot establishment phase.

[0180] Closed-loop control: In control strategy ②, the target expected value for stiffness tracking is specifically the midline of the interval. To adapt to the target value, ;

[0181] Phase transition warning: When Continue to exceed When combined with other criteria, it serves as one of the key judgment bases for entering the critical stage of assembly completion.

[0182] Step S200: Real-time acquisition of displacement and pressure data

[0183] Displacement and pressure data during the assembly process are collected in real time using displacement and pressure sensors, and the acquired data is then filtered.

[0184] Step S300: Calculation and tracking of equivalent press-fit stiffness

[0185] Based on synchronously collected pressure data and displacement data Dynamically construct pressure-displacement curves ( (Curve), instantaneous equivalent press-fit stiffness is calculated in real time using the finite difference method. , , Indicates the hydraulic system at the previous moment Up to the current moment The pressure increase, Indicates the moment before the bearing Up to the current moment The displacement increment.

[0186] In this embodiment, The physical essence of it is the system equivalent stiffness that comprehensively characterizes the coupling effect of the hydraulic system's flow resistance, conical surface dynamic friction, and material contact stiffness. It can be used to objectively identify and determine the endpoint of the continuous process of "no-load stroke → elastic interference establishment → yield saturation", and can replace the traditional method based on a fixed threshold.

[0187] In this preferred embodiment, to ensure numerical stability, when the displacement increment... Below the preset minimum threshold At that time, pause updates used for decision-making. The value is determined and the valid value from the previous time step is retained, serving as the basis for judgment in subsequent step S400. Minimum threshold. The value is set to 3 to 5 times the resolution of the displacement sensor and the sum of the peak value of the equivalent displacement noise caused by the inherent pulsation of the hydraulic system, in order to avoid instability in the differential calculation when the displacement increment is too small.

[0188] Step S400 includes two parallel channels. One channel is used to determine the assembly stage of the workpiece according to predetermined rules, and the other channel is used to determine whether the assembly endpoint has been reached and whether there is an abnormality in the assembly process. If either the endpoint judgment strategy or the abnormality judgment strategy is satisfied, the shutdown process is executed; otherwise, if neither is satisfied, the next step is entered.

[0189] I. Strategies for determining the idle travel phase, such as Figure 4 As shown;

[0190] Target for assessment: Identify the stage in which the bearing inner ring has not yet made effective mechanical contact with the journal tapered surface during axial advance.

[0191] Judgment condition: within the first continuous time window The following conditions 1, 2, and 3 must be met simultaneously.

[0192] Condition 1 (Core Stiffness Criterion 1): Real-time calculated instantaneous equivalent press-fit stiffness Does it meet the requirements? , This indicates the initial contact stiffness threshold.

[0193] Condition 2 (Effective Displacement Criterion): The axial displacement continues to increase effectively, i.e., the rate of change of displacement. , This represents the minimum effective speed threshold, used to eliminate stagnation artifacts caused by sensor noise.

[0194] Condition 3 (Low-pressure state criterion): The system drive oil chamber pressure simultaneously satisfies the following two conditions:

[0195] , Indicates the initial contact pressure threshold, for example: ≈5MPa, used to physically distinguish the uncontacted state.

[0196] , represents the upper limit of the safety pressure during no-load travel, and is used as an absolute safety boundary.

[0197] In this embodiment, preferably, during the first continuous time window If conditions one, two, and three are met simultaneously, the current process is considered to be in an idle phase, and the first continuous time window is selected. It can filter out transient disturbances in the signal and can be matched with the sampling period of the control system (e.g., 100Hz).

[0198] II. Strategies for Judging the Contact and Over-exertion Stages, such as Figure 4 As shown

[0199] Judgment objective: To accurately identify the process stage in which the interference fit gradually builds up within the elastic deformation range of the material after the inner ring of the bearing and the tapered surface of the journal have made effective contact.

[0200] Judgment condition: In Conditions four and five must be met simultaneously within the (stable duration threshold) time.

[0201] Condition 4 (Core Stiffness Criterion 2):

[0202] First, confirm the contact start point: After the no-travel phase ends, detect contact points in two consecutive sampling cycles. If the contact initiation stiffness threshold is set, then this initiation time is established as the contact initiation point, and this is used as the zero point for timing and displacement calculation in this stage.

[0203] Then determine Is it located in Within the interval: Instantaneous equivalent press-fit stiffness from the point of initial contact. The value enters and is mainly located in the dynamic reference range corresponding to the current displacement point. Inside, This represents the lower boundary value of the dynamic reference interval corresponding to the current displacement point. This represents the upper boundary value of the dynamic reference interval corresponding to the current displacement point.

[0204] Condition 5 (Criterion for Rate of Change 1): From the point of initial contact, in the... Within the time window, the instantaneous equivalent press stiffness satisfies the non-decreasing condition at the window endpoints:

[0205] ;

[0206] in, Indicates instantaneous equivalent press stiffness. For time Instantaneous equivalent compression stiffness at the initial moment, This indicates the preset noise tolerance threshold.

[0207] This criterion ensures that during the elastic interference establishment phase, the stiffness evolution conforms to the physical laws of material elastic deformation on a macroscopic time scale (i.e., the overall stiffness does not decrease), while also accommodating normal fluctuations in actual measurements, compared to requiring instantaneous rate of change. The strict criteria are introduced by this criterion through noise tolerance. and stable duration threshold It effectively filters out instantaneous fluctuations, and only when the stiffness at the end of the window decreases beyond the tolerance limit compared to the stiffness at the beginning is it judged as an abnormal trend.

[0208] In this embodiment, the assembly process is determined to have entered and be in the contact and interference establishment stage (i.e., the elastic interference establishment stage) only when all conditions four and five above are met from the contact initiation point. This stage lasts until... The evolution continues until the assembly completion critical stage strategy is satisfied. Further, the stable duration threshold for the contact and interference establishment stage is determined. (Approximately 10 control cycles) This duration is sufficient to cover the pressure response delay of the hydraulic system and filter measurement noise, confirming a stable physical process.

[0209] III. Strategies for determining the critical stage of assembly completion, such as... Figure 4 As shown

[0210] Judgment objective: To accurately identify the critical region where the mechanical behavior of the bearing inner ring material transitions from elastic deformation to yielding or interference saturation.

[0211] Judgment conditions: The following conditions six, seven and eight must be met simultaneously.

[0212] Condition 6 (Stiffness Detachment Criterion): Instantaneous Equivalent Press-fit Stiffness Continuously exceeding the upper boundary of the dynamic reference interval corresponding to the current displacement point And the excess meets the requirements. , Indicates the relative out-of-tolerance threshold, preferred = 0.1, or 10%, this state lasts for a duration of 10%. Preferred .

[0213] Condition 7 (Criterion 2 for Rate of Change): Rate of change of equivalent press-fit stiffness Greater than the preset critical rate of change threshold Critical rate of change threshold It is a calibration value greater than zero.

[0214] Condition 8 (Displacement Safety Criterion): Real-time measured axial displacement Not less than the minimum displacement threshold determined according to the design drawings .

[0215] In this embodiment, when all of the above conditions six, seven and eight are met simultaneously, the assembly process is determined to have entered the critical stage of assembly completion (i.e., the yield saturation critical region).

[0216] IV. Endpoint Judgment Strategies, such as Figure 5 As shown;

[0217] Judgment Target: The strategy adopts a dual-criteria coupled judgment logic that combines the main criterion of physical state with the auxiliary criterion of process parameters, aiming to uniquely and reliably identify the optimal assembly endpoint determined by the mechanical behavior of materials.

[0218] Judgment conditions: In addition to meeting the critical stage conditions for assembly completion, the following conditions nine and ten must also be met.

[0219] Condition Nine (Physical State Channel Criterion):

[0220] , This represents the material's saturation stiffness threshold.

[0221] , This represents the critical rate of change threshold, which can be used as one of the criteria to confirm that the equivalent press-fit stiffness has entered a defined nonlinear rapid increase stage.

[0222] Condition 10 (Process Parameter Channel Criterion):

[0223] Displacement safety range: The actual displacement must be within the theoretical interference displacement range required by the design. Inside. Among them, This represents the minimum displacement threshold determined according to the design drawings. This indicates the maximum displacement threshold determined according to the design drawings; This represents the expected lower limit of pressure, determined based on the minimum allowable interference in the design. This indicates the upper limit of the expected pressure, determined based on the maximum allowable interference in the design.

[0224] Reasonable range of pressure: The requirement is that the real-time pressure is within the expected pressure range. , This represents the expected lower limit of pressure, determined based on the minimum allowable interference in the design. This represents the upper limit of the expected pressure determined based on the maximum allowable interference in the design, which can be used for further cross-validation of the endpoint determination.

[0225] V. Anomaly detection strategies, such as Figure 6 As shown and Figure 7 As shown;

[0226] Target assessment: Define and quantify triggering conditions and protective actions for severe faults unique to hydraulic assembly systems.

[0227] Judgment criteria: An anomaly is defined as one that meets any one of the following three conditions.

[0228] The first item: Diagnosis of mechanical jamming and cold welding faults. The physical essence of this fault is metal seizing between the inner ring of the bearing and the tapered surface of the journal, the presence of hard foreign objects, or complete failure of lubrication leading to a sharp increase in dry friction, thereby causing fluid-mechanical deadlock. Its typical physical characteristics are: hydraulic system thrust (pressure) P The rate of increase is sharp, while the actual axial displacement of the bearing inner ring relative to the journal stagnates.

[0229] Criteria for determining jamming and cold welding faults: in the second continuous time window Both conditions eleven and twelve are satisfied simultaneously.

[0230] Condition 11 (Criterion for Abnormal Pressure-Displacement Relationship): Instantaneous Equivalent Press-Fit Stiffness Exceeding the upper boundary value of the dynamic reference interval This is multiples of the given value. Therefore, the inequality is satisfied: in, The safety factor for jamming is a constant greater than 1, which is preferred. =3.0.

[0231] Condition 12 (Displacement Stagnation Criterion): The absolute value of the actual axial displacement change rate of the bearing inner ring is less than the preset displacement stagnation threshold, that is... , Indicates the rate of change of displacement. This represents the displacement stagnation threshold.

[0232] In this embodiment, within the time window If conditions eleven and twelve are met simultaneously, it is determined that there is a jamming and cold welding fault. The preferred time is 50ms to filter out transient interference in control fluctuations or measurement signals.

[0233] The second item: Diagnosis of hydraulic system leakage and failure. The physical nature of this failure is that there is internal or external leakage in the hydraulic pipeline, joint or seal, or failure of the hydraulic pump or drive motor, which causes the system to be unable to build up enough oil pressure to push the piston. Its physical characteristics are: the system pressure cannot be built up normally, and at the same time, the inner ring of the bearing has no effective axial displacement.

[0234] Leakage and failure detection criteria: Starting from the issuance of the start-up press-fit command, within the preset leakage diagnosis time window. It simultaneously satisfies conditions thirteen, fourteen, and fifteen.

[0235] Condition 13 (Pressure build-up failure criterion): Timing begins from the start of the pressure build-up command issued by the self-control unit, within the preset leak diagnosis time window. Within the system, the real-time system pressure is consistently below the hydraulic system's pressure build-up threshold. .

[0236] Condition 14 (Criterion for Invalid Displacement Growth): Within the same time window Internal, the actual cumulative displacement increment of the bearing Less than the invalid displacement threshold .

[0237] Condition 15 (System Stiffness Anomaly Criterion): Within the time window The average instantaneous equivalent press-fit stiffness calculated internally Significantly lower than the displacement point at the start of the window The expected stiffness based on the benchmark, that is, satisfying , This represents a stiffness anomaly setting factor less than 1, for example... =0.5, Indicated based on lower boundary function Displacement point The corresponding expected stiffness, that is, the lower boundary function of the dynamic reference interval in the displacement... The lower limit of stiffness can be obtained by querying or calculating.

[0238] In this embodiment, if within the leak diagnosis time window If conditions thirteen, fourteen, and fifteen are met simultaneously, it is determined that there is a leakage and failure.

[0239] The third item is the absolute safety boundary diagnosis, which serves as the ultimate safety guarantee to prevent the system pressure or displacement from exceeding the mechanical bearing limits of components (bearings, journals) due to abnormal control logic, sensor failure, or other unforeseen reasons, thus avoiding plastic deformation or structural damage.

[0240] The criteria for determining whether the absolute safety boundary has been exceeded include: satisfying one of conditions sixteen or seventeen.

[0241] Condition 16 (Pressure Boundary): , This represents the absolute maximum pressure determined by the component material strength and safety factor.

[0242] Condition 17 (Displacement Boundary): , It represents the absolute maximum displacement determined by the design drawings and fit tolerances.

[0243] In this embodiment, if any one of the above conditions sixteen or seventeen is met, it is considered that the safety boundary has been exceeded, and the corresponding emergency operation must be performed unconditionally and immediately.

[0244] In step S400, the shutdown process includes performing different shutdown operations based on the shutdown reason. In this embodiment, the preferred operation is as follows: Figure 8 As shown:

[0245] If the endpoint judgment strategy is met, the hydraulic system is controlled to stop pressurizing and maintain pressure for a period of time (e.g., 3 to 5 seconds) before stopping and depressurizing.

[0246] If the jamming and cold welding faults in the abnormal judgment strategy are met, or if the safety boundary is exceeded, the hydraulic system is controlled to shut down and depressurize.

[0247] If the leakage and failure faults in the anomaly judgment strategy are met, the hydraulic system is controlled to shut down urgently and the alarm procedure is initiated.

[0248] In this embodiment, the shutdown process preferably includes generating an electronic file after the shutdown operation is performed. The electronic file in this embodiment includes: task identifier, timing data, event logs, and parameters and results. Preferably, the electronic file is encapsulated using the OPC UA protocol, adapting to the standard data interface of the MES / PLM system, enabling automatic uploading and traceability of assembly process data.

[0249] The task identifier includes: a unique task ID, bearing model, operator, equipment number, and timestamp. Preferably, the task identifier also includes journal specifications, material, etc.

[0250] The timing data includes: timing data collected synchronously at a fixed frequency (e.g., 100Hz), specifically including time, pressure, displacement, and calculated equivalent press-fit stiffness. Preferably, the synchronously collected timing data also includes control commands output by the system (e.g., proportional valve opening or pressure setpoint).

[0251] The event log includes: the start and end points of key stages (idle travel, contact and interference, critical stage) recorded in chronological order, and abnormal event points.

[0252] Among them, anomaly event points are structured data units in the archive that record abnormal situations, including:

[0253] Event Time: The precise timestamp at which the exception was confirmed and triggered by the system;

[0254] Event type: A unique code for the anomaly. For example, stuck and cold solder joint failures are assigned the code 001, leaks and failures are assigned the code 002, and so on.

[0255] Status snapshot: Relevant parameters at the moment the anomaly is triggered or activated. The relevant parameters should include at least the pressure data, displacement data, equivalent press-fit stiffness data, etc. at this moment.

[0256] System response: Commands executed automatically by the system, such as emergency pressure relief, pump stop alarm, etc.

[0257] The parameters and results include: the preset process parameters, the actual control parameters, the final assembly result (i.e. whether it is qualified or not), and key result data including the final displacement.

[0258] In this embodiment, if the assembly task is ultimately determined to be qualified, the data of successful assembly in this system is also the displacement. -Stiffness The data sequence is stored in the database, and in subsequent processing, the displacement after filtering and alignment during the contact and interference establishment stages is processed. -Stiffness The data sequence serves as the dynamic reference interval for the next calculation of the assembly task, enabling the system to continuously track and adapt to long-term process changes. Further optimization allows the system to re-execute steps S121 to S124 according to a preset strategy (such as after 10 successful assemblies or periodic automatic triggering) when calculating the dynamic reference interval, updating the mean value of all displacement points. Standard deviation And the interval boundary, thereby realizing self-learning and incremental optimization of the dynamic benchmark interval.

[0259] Step S500: Based on the different assembly stages in step S400, different control strategies are adopted for the hydraulic system. After the control is completed, the system returns to step S200 to continue collecting data, and then re-enters step S400 for judgment, forming a closed loop. Figure 1 and Figure 9 As shown.

[0260] If the system is in the idle phase, control strategy ① is used to control the hydraulic system to maintain a constant speed propulsion mode. Control strategy ① includes:

[0261] Control objective: To bring the inner ring of the bearing close to the journal cone at the highest safe and permissible constant speed, thereby eliminating mechanical clearance.

[0262] Strategy details: Output a fixed opening command to the electro-hydraulic proportional valve of the hydraulic system to drive the hydraulic pump station at a constant flow rate. The operation allows the drive end of the hydraulic system (which is the hydraulic nut piston) to obtain a constant propulsion speed. At the same time, the pressure is continuously monitored to ensure that it remains below the preset safe pressure limit for no-load travel.

[0263] If the system is in the contact and interference establishment phase, then control strategy ② is used to control the hydraulic system, making it operate in a stiffness tracking-pressure closed-loop mode. Control strategy ② includes:

[0264] Control objective: By adjusting the output pressure of the closed-loop control system, the instantaneous equivalent press-fit stiffness is made to track and stabilize near the desired trajectory (such as the center line of the interval) within the dynamic reference interval, thereby achieving precise and stable establishment of the interference fit.

[0265] Strategy content: (with a fixed control cycle) Preferred =10ms, executed in a loop)

[0266] Data Acquisition and Calculation: Obtaining the pressure at the current moment and displacement ,calculate and deviation , The midline of the dynamic reference interval;

[0267] Closed-loop regulation: Input to a proportional-integral controller, the controller outputs a pressure regulation amount. ;

[0268] Command output: Generate a new pressure setpoint. The signal is sent to the electro-hydraulic proportional valve for execution, thereby increasing the instantaneous equivalent press-fit stiffness. Stable within the dynamic reference range Inside.

[0269] If the system is at the critical stage of assembly completion, control strategy ③ is used to control the hydraulic system to slowly move it towards the endpoint judgment. Control strategy ③ includes:

[0270] Control objective: To complete the final exploration and confirmation of the physical inflection point of the material's yield saturation at an extremely low speed, and to safely terminate the assembly process.

[0271] Strategy content:

[0272] Switch to low-speed probe: Immediately reduce the hydraulic system flow command to the preset endpoint probe flow rate. , Much smaller than constant flow ,For example It is 0.1 to 0.3 times. ;

[0273] Entering the endpoint determination state: In this state, the endpoint determination strategy defined above is continuously monitored at high frequency. Once all criteria are met, the corresponding shutdown operation is executed immediately (within the next control cycle).

[0274] Preferably, in this embodiment, during the execution of the above control strategy ②, if the instantaneous equivalent press-fit stiffness Exceeding the dynamic reference range If the critical stage of assembly completion is met, it is necessary to determine whether control strategy ② is terminated and control strategy ③ is switched. If it is determined that the contact and interference establishment stage is still in the stage, the regression control step needs to be executed.

[0275] The regression control steps include:

[0276] Step 1 (Action): Pause pressure setting Active growth (i.e., making) Maintain current pressure;

[0277] Step Two (Observation): Start a time period of... Observation timer;

[0278] Step 3 (Decision):

[0279] If in Inside, If the system returns to the dynamic reference range, the instantaneous disturbance is considered to have ended, and the closed-loop control steps of control strategy ② above will continue to be executed. Otherwise, the hydraulic system will be shut down and an alarm program will be activated.

[0280] like After the timeout, If the system still fails to return to the dynamic reference range, it is determined to be a continuous abnormal deviation, triggering a process deviation alarm and suspending assembly. At the same time, the hydraulic operation circuit is locked. After manual troubleshooting and confirmation, the lock can be released by manual reset. The process parameters can be adjusted according to the cause of the fault before restarting assembly.

[0281] In this embodiment, Maintaining the dynamic reference range has the following advantages:

[0282] Direct evidence of process consistency: The stability within the range generated based on historical qualified data is an online quantitative proof that the mechanical path of this assembly process is consistent with successful experience, providing a process guarantee for the consistency of the results.

[0283] Adaptive control: The dynamic reference range itself compensates for common system disturbances; therefore, control... By tracking this range, an adaptive control that integrates feedforward (historical experience) and feedback (real-time deviation) is achieved.

[0284] To ensure the reliability of physical endpoint determination: only by establishing a stable and controlled process during the contact and interference establishment phases can this be achieved. Only by establishing an evolutionary baseline can subsequent nonlinear surges be uniquely and reliably attributed to material yielding, thus eliminating misjudgment in principle.

[0285] Example 3:

[0286] This embodiment three discloses a control system for assembling tapered bore bearings using a hydraulic system. The hydraulic system in this embodiment is configured as the hydraulic system in embodiment one, such as... Figure 10 As shown.

[0287] The control system includes a sensing unit, a control unit, and a data storage and interaction unit.

[0288] The sensing unit includes a pressure sensor and a displacement sensor. The pressure sensor is connected to the pressure supply unit of the hydraulic system, specifically between the pressure supply unit and the hydraulic nut, and is used to acquire the pressure data of the hydraulic system and transmit it to the control unit. The displacement sensor is mounted on a rigid bracket and is axially aligned with the bearing to be installed, and is used to acquire the axial displacement data of the bearing and transmit it to the control unit.

[0289] The control unit is connected to the hydraulic system and incorporates the control method described in Embodiment 2. The control unit is used to control the hydraulic system to change its operating parameters; for example, it is connected to a hydraulic pump station and a high-response electro-hydraulic proportional valve. This control unit is equipped with the highest hardware interrupt priority logic, enabling parallel execution of endpoint judgment and fault diagnosis such as mechanical jamming and hydraulic leakage, achieving millisecond-level active safety protection. The control unit can be an industrial PLC or embedded IPC with high-speed floating-point arithmetic capabilities.

[0290] The data storage and interaction unit is connected to the control unit via interfaces such as industrial Ethernet to realize human-machine interaction and communication. The data storage and interaction unit includes a data storage unit and an interaction unit. The data storage unit is bidirectionally connected to the control unit. The data storage unit stores a database containing historical qualified assembly data. The interaction unit is bidirectionally connected to both the data storage unit and the control unit. The interaction unit is used to exchange information with the outside world. For example, the generated electronic files are sent to the outside world through the interaction unit. The interaction unit can also set and modify relevant parameters.

[0291] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A control method for assembling tapered bore bearings using a hydraulic system, characterized in that, include: Step S100: Begin; Step S200: Collect pressure data of the hydraulic system and displacement data of the bearing, and preprocess the data; Step S300: Based on pressure data and displacement data, obtain the equivalent press-fit stiffness; Step S400: Based on the equivalent press-fit stiffness, determine the current assembly stage according to the predetermined rules, and execute the endpoint judgment strategy and the abnormal judgment strategy. If either the endpoint judgment strategy or the abnormal judgment strategy is met, execute the shutdown process; otherwise, proceed to the next step. Step S500: Apply different control strategies to the hydraulic system according to the different assembly stages in step S400, and then return to step S200. Step S100 includes: Step S110: Load preset process parameters; Step S120: Calculate the dynamic benchmark interval based on historical qualified data. ,include: Step S121: Historical Data Filtering Retrieve from the database based on the specifications of the workpiece to be assembled; Select the most recent Historical records of substandard assembly; Step S122: Data Extraction and Processing From each selected historical record, extract the original data sequence of its contact and interference establishment phases to obtain... Set of data pairs: , and Representing the first The displacement and stiffness sequences in the records, ; The original displacement data and equivalent press-fit stiffness data of each sequence are filtered; Instantaneous equivalent press-fit stiffness in each sequence First satisfaction The data points are used as the contact start point. This represents the contact initiation stiffness threshold. Using this contact initiation point as the displacement reference, the displacement coordinates of each sequence are zeroed out, and the data from the empty travel stage before the contact initiation point are discarded. The sequences are aligned along the displacement axis using the same physical starting point. Let the common displacement analysis interval used to construct the dynamic reference interval after alignment be denoted as . ; Common displacement interval Evenly divided into Discrete displacement points: ; Step S123: Calculation of statistics For each discrete displacement point By using linear interpolation, the discrete displacement points of each sequence are obtained. The corresponding stiffness value This forms a stiffness sample set for that displacement point: ; Through formula Calculate the mean of the baseline interval, where This represents the mean of the baseline interval. Indicates the first The sequence in The stiffness value; Indicates the smoothing factor; Indicates based on the previous The previous round calculated from the sequence Mean; Based on stiffness sample set Calculate the standard deviation of this set. Used to quantize at the displacement point Within the normal fluctuation range of stiffness; Step S124: Generate the dynamic reference interval for this assembly. Through formula Calculate the lower boundary function of the dynamic reference interval. , Indicates the coverage factor; Through formula Calculate the upper boundary function of the dynamic reference interval .

2. The control method according to claim 1, characterized in that, In step S300, after real-time filtering of the collected pressure and displacement data, a pressure-displacement curve is dynamically constructed, and the instantaneous equivalent press-fit stiffness is calculated in real time using the finite difference method. , , Indicates the hydraulic system at the previous moment Up to the current moment The pressure increase, Indicates the moment before the bearing Up to the current moment The displacement increment.

3. The control method according to claim 2, characterized in that, when Below the preset minimum threshold At that time, pause updates used for decision-making. The value is determined and the valid value from the previous moment is retained. The valid value from the previous moment is then used for judgment in step S400.

4. The control method according to any one of claims 1 to 3, characterized in that, The predetermined rules for determining the assembly stage in step S400 include: If in the first consecutive time window If all three conditions are met simultaneously, it is determined to be an empty travel phase; Condition 1, Core Stiffness Criterion 1: , Indicates instantaneous equivalent press-fit stiffness; Indicates the contact initial stiffness threshold; Condition 2, Effective Displacement Criterion: Rate of Change of Displacement ; Indicates the minimum effective speed threshold; Condition 3, Low-pressure state criterion: Current moment pressure and , Indicates the initial contact pressure threshold. Indicates the upper limit of safety pressure during no-load travel; If it continues If conditions four and five are met simultaneously within a certain time period, it is determined to be the contact and interference establishment stage; Condition 4, Core Stiffness Criterion 2: lie in Within the interval, This represents the lower boundary value of the dynamic reference interval corresponding to the current displacement point. This represents the upper boundary value of the dynamic reference interval corresponding to the current displacement point; Condition 5, Criterion 1 for rate of change: In the above Within a given time period, the equivalent press-fit stiffness satisfies the non-decreasing condition at the window endpoints: in, Indicates instantaneous equivalent press stiffness. Indicates the time Instantaneous equivalent compression stiffness at the initial moment, This indicates the preset noise tolerance threshold. If conditions six, seven, and eight are met simultaneously, the assembly is considered to be in the critical stage of completion. Condition 6, Stiffness Detachment Criterion: continued Time greater than and , Indicates the relative out-of-tolerance threshold; Condition 7, Criterion 2 for rate of change: Rate of change of equivalent press-fit stiffness , This represents the critical rate of change threshold; Condition 8, Displacement Safety Criterion: , Indicates the current time The displacement, This indicates the minimum displacement threshold determined according to the design drawings.

5. The control method according to claim 4, characterized in that, The endpoint determination strategy includes satisfying the following two conditions in addition to meeting the critical stage conditions for assembly completion: Condition 9, Physical State Channel Criterion: and ,in, Indicates the material's saturation stiffness threshold; Condition 10, Criteria for Process Parameter Channels: and , This represents the minimum displacement threshold determined according to the design drawings. This indicates the maximum displacement threshold determined according to the design drawings; This represents the expected lower limit of pressure, determined based on the minimum allowable interference in the design. This indicates the upper limit of the expected pressure, determined based on the maximum allowable interference in the design.

6. The control method according to claim 4, characterized in that, Anomaly detection strategies include diagnoses that meet any of the following criteria: The first item, diagnosis of jamming and cold welding faults, includes the judgment criteria in the second continuous time window. Both conditions eleven and twelve are satisfied simultaneously. Condition 11, Criterion for Abnormal Pressure-Displacement Relationship: , Indicates instantaneous equivalent press stiffness. Indicates the safety factor for jamming; This represents the upper boundary value of the dynamic reference interval corresponding to the current displacement point; Condition 12, Criterion for Displacement Stagnation: Rate of Change of Displacement absolute value , Indicates the displacement stagnation threshold; The second item is the diagnosis of hydraulic system leaks and failures. The judgment criteria include timing from the issuance of the start press-fit command within a preset leak diagnosis time window. The condition simultaneously satisfies conditions thirteen, fourteen, and fifteen. Condition 13, Failure Criterion for Pressure Establishment: consistently less than , This indicates the pressure build-up threshold of the hydraulic system; Condition 14, Criterion for Invalid Displacement Growth: Less than , Indicates time window The actual cumulative displacement increment within, Indicates the invalid displacement threshold; Condition 15, Criterion for System Stiffness Anomaly: Time Window Average equivalent press-fit stiffness obtained from internal calculation , This represents a stiffness anomaly setting factor less than 1. Indicated based on lower boundary function Time window Displacement point at the start time The corresponding lower limit of stiffness; The third item is the absolute safety boundary diagnosis, and the judgment condition includes meeting one of condition sixteen or condition seventeen. Condition 16, Pressure Boundary: , This represents the absolute maximum pressure determined by the component material strength and safety factor. Condition 17, Displacement Boundary: , It represents the absolute maximum displacement determined by the design drawings and fit tolerances.

7. The control method according to claim 6, characterized in that, In step S400, the shutdown process includes performing different shutdown operations based on the shutdown reason; If the endpoint judgment strategy is met, the hydraulic system is controlled to stop pressurizing and maintain pressure for a period of time before stopping and depressurizing. If the jamming and cold welding faults in the abnormal judgment strategy are met or the safety boundary is exceeded, the hydraulic system is controlled to shut down and depressurize in an emergency. If the leakage and failure faults in the anomaly judgment strategy are met, the hydraulic system is controlled to shut down urgently and the alarm procedure is initiated.

8. The control method according to claim 7, characterized in that, The shutdown process also includes generating an electronic record after the shutdown operation is performed; Electronic archives include task identifiers, time-series data, event logs, and parameters and results; The task identifier includes a unique task ID, bearing model, operator, equipment number, and timestamp; Time-series data includes time, pressure, displacement, and equivalent press-fit stiffness; The event log includes the start and end points of the assembly stages and abnormal event points recorded in chronological order; The parameters and results include the preset process parameters, the actual control parameters, the final assembly results, and key result data including the final displacement.

9. The control method according to claim 4, characterized in that, In step S500, different control strategies are adopted for the hydraulic system according to different assembly stages, including: If it is in the no-stroke stage, a fixed opening command is output to the hydraulic system to drive the hydraulic system at a constant flow rate. This operation allows the drive end of the hydraulic system to achieve a constant propulsion speed. ; If the system is in the contact and interference setup phase, then the closed-loop control steps are initiated, including first calculating... and deviation , Indicate the midline of the dynamic reference interval, then The input is sent to the proportional-integral (PI) controller, which then outputs the pressure regulation amount. Finally, a new pressure setpoint is generated. And Send to the hydraulic system for execution, to achieve instantaneous equivalent press-fit stiffness Stable within the dynamic reference range Inside; If the assembly is at a critical stage, reduce the flow rate of the hydraulic system to the preset endpoint detection flow rate. , .

10. The control method according to claim 9, characterized in that, During the contact and interference fit establishment phase, if the instantaneous equivalent press-fit stiffness Exceeding the dynamic reference range Then, the regression control steps are executed, including: Step 1: Let ; Step 2: Start a time period of Observation timer; Step 3: If in Inside, If the system returns to the dynamic reference range, the closed-loop control steps continue; otherwise, the hydraulic system is shut down and an alarm procedure is initiated.

11. A control system for assembling tapered bore bearings using a hydraulic system, characterized in that, include: The sensing unit includes a pressure sensor and a displacement sensor, both connected to the control unit. The pressure sensor is connected to the hydraulic system to acquire pressure data, and the displacement sensor is set to correspond to the bearing to be installed to acquire the bearing displacement data. The control unit has a built-in control method according to any one of claims 1 to 10 for controlling a hydraulic system, wherein the hydraulic system drives the bearing to be installed to move along its axial direction. The data storage and interaction unit is bidirectionally connected to the control unit.

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